Blockchain A-Z: Build a Blockchain, Crypto, & Smart Contract

Explore how a blockchain forms a cryptographically linked chain of blocks, each with its own hash and the previous hash, creating an immutable ledger and protecting against tampering.

Explore how the immutable ledger of blockchains links blocks with cryptographic hashes, preventing tampering and protecting ownership records like title deeds in government ledgers.

Expand the blockchain across thousands of computers in a distributed peer-to-peer network, use majority consensus to detect tampering, and restore data when errors occur, enabling trust in a trustless environment.

Miners iterate nonces to generate hashes below a target, using SHA-256, leading zeros, and the avalanche effect to secure a block and advance the blockchain.

Define a get_previous_block method that returns the last block from the blockchain using self.chain[-1], setting up the upcoming proof of work and mining step.

Explore how a proof of work uses a hard to find, easy to verify puzzle with previous and new proofs, a non-symmetric sha256 hash, and four leading zeros.

Develop a blockchain validation function that checks each block's proof of work (four leading zeros) and the previous hash using a sha256 hash of sorted json blocks.

Learn to implement is_chain_valid in this blockchain tutorial, validating each block by comparing previous hashes and verifying proof of work with four leading zeros, completing part one.

Implement a Flask route mine_block to mine a new block by solving proof_of_work with the previous block, then return the mined block via JSON with HTTP 200.

Demonstrate the homework solution by using the is chain valid function to check blockchain validity via the is valid get request and test it with Postman.

Bitcoin's monetary policy is controlled by its software, featuring a halving every 210,000 blocks, four years, reducing the reward from 50 to 25 to 12.5, with a 21 million cap.

Discover how mining pools combine hashing power to distribute the nonce search across members, avoid double work, and reward contributions proportionally while relieving solo miners' headaches.

Explore how orphaned blocks occur when two chains exist, learn why the longest chain wins, and why six confirmations protect against double spending and mempool activity.

Create the Hadcoin cryptocurrency by extending the module 1 blockchain, decentralize the network across multiple nodes, mine blocks, and implement consensus using Python, Flask, and the requests library.

Enable a post request to add a transaction to the blockchain by posting a JSON with sender, receiver, and amount; return the next block index and a 201 status.

Implement the replace_chain endpoint to replace the chain with the longest one, using is_chain_replaced, a get request, and a json node list for network synchronization.

Prepare JSON files for node addresses and transactions, set up three Python servers on ports 5001–5003, and format a ready-to-post had coins transaction for Postman.

Explore Ethereum fundamentals, smart contracts, and decentralized applications. Understand the Ethereum Virtual Machine, gas, DAOs, forks, initial coin offerings, white papers, and Web 3.0 implications.

Explain that smart contracts are code running on the blockchain, executing if this then that and updating state across all nodes. Contrast Bitcoin Script and Solidity's Turing completeness and loops.

Explore soft and hard forks with real-life Bitcoin and Ethereum examples, compare tightening versus loosening rules, and understand how block size debates and SegWit shape the blockchain.